Heathrow is one of the busiest airports in the world, it is key to ensure continued support on their projects. FSi Ltd were approached to provide a product to seal new and existing service penetrations in walls and floors up to 120 minutes fire resistance. This has been achieved through the installation of FSi Ltd products by Mitie Fire providing full compartmentalization. Mitie, BAA and Firestopit have a long working relationship throughout the Heathrow Airport complex, which requires careful planning and installation decisions to ensure the correct products are used.